Bolt won 200m silver at the 2007 World Championships behind Gay

World 100m record holder Usain Bolt is unsure whether he will compete over the distance at the Beijing Olympics.

After setting a new 100m mark of 9.72 seconds last weekend, the Jamaican said he would "definitely" double up.

But on Tuesday, he said: "I have been dedicating my whole life to the 200m and would really like to get the gold."

He said coach Glen Mills would have the final say. "This has been my fourth year with my coach and he has made nothing but good decisions," he said.

"It sounds like I may be doubling, but we are not sure yet...(I will run) the 200m for sure.

"If Glen decides I should do only the 200m, I am fine with that because I am sure he has his reasons and they would be good reasons."

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"I'm not going there to race Asafa, I'm going there to make the team," said the 21-year-old.

"Maybe on another day, at another track meet if we meet, that would be a showdown."

Bolt hinted he could run in the London Grand Prix (25-26 July), where Powell and US world champion Tyson Gay are scheduled to race in the 100m, but added nothing was decided.